The present invention relates generally to an elongated stretch releasing adhesive tape article with a geometry that provides differential adhesive properties, and in particular, to a geometry that provides regions of reduced adhesion to form pull-tabs.
Stretch releasing adhesive tapes represent an emerging class of high performance pressure-sensitive adhesives combining strong holding power with clean removal and no surface damage. Such stretch releasing adhesive tapes are useful in a wide variety of assembling, joining, attaching, and mounting applications.
Adhesive tape strips that can be cleanly removed from a surface by stretching the tape strip are known in the patented prior art. The Korpman U.S. Pat. No. 4,024,312, for example, discloses a highly conformable adhesive tape including a highly extensible and elastic backing film laminated with an adhesive layer. The backing film possesses a lengthwise elongation at break of at least about 200%. The tape is easily stretchable and may be removed from a surface by stretching the tape lengthwise in a direction substantially parallel to the surface. German Patent No. 33 31 016 discloses a high elasticity, low plasticity adhesive film based on a thermoplastic rubber and tackifying resins, wherein the adhesive bond can be broken by stretching the adhesive film in the direction of the plane of the adhesive bond.
The Kreckel et al. U.S. Pat. No. 5,516,581, assigned to the same assignee as the present invention, discloses a removable adhesive tape having a highly extensible and substantially inelastic backing coated with a layer of pressure sensitive adhesive. The adhesive tape can be removed from a substrate without damaging the substrate by stretching the tape in a direction substantially parallel to the surface of the substrate. The tape backing has a lengthwise elongation at break of from about 150% to about 1200%, a Young""s modulus of at least about 2,500 psi to about 72,500 psi, and an elastic recovery of less than about 50% after being stretched and removed. PCT International Publication No. WO 95/06691 discloses a removable foam adhesive tape comprising a backing including a layer of polymeric foam, and a layer of pressure-sensitive adhesive coated on at least one surface of the backing. The foam layer of the backing has a thickness of about 30 to about 1000 mils, and the backing has a lengthwise elongation at break of from about 50% to about 1200%, and a Young""s modulus of less than about 2,400 psi.
Commercial stretch releasing adhesive tapes include the product sold under the trade designation COMMAND by Minnesota Mining and Manufacturing Company, St. Paul, Minn., and the product sold under the trade designation POWER-STRIPS by Beiersdorf A G, Hamburg, Germany. These products are currently manufactured as discrete strips with one end of the strip including a non-adhesive pull tab to facilitate stretching of the strip during removal. The adhesive surfaces of the strip are additionally protected with a release liner.
Desirable for certain applications is an elongated stretch releasing adhesive tape strip of indefinite length which can be formed into a roll or stack from which segments of selected length can be cut depending on the end use application. The difficulty with providing a long length of stretch releasing tape which can be cut to a selected length is the ability to provide a pull tab at a specific location on the cut strip to serve as a grasping area for stretching the strip from a surface at the time of removal.
PCT International Publication No. WO 98/06652 discloses a length cutting fixture that can be used to form a non-adhesive pull tab or xe2x80x9cgripperxe2x80x9d at the end of a long length of a conventional single-sided adhesive tape. The length cutting fixture also serves to cut the long length of tape, now including the gripper, to any selected length. The gripper is formed by folding the end of the tape back onto itself. Such a length cutting fixture, however, cannot be used to form a non-adhesive pull tab on a double-sided adhesive tape.
It is therefore desirable to provide a stretch releasing adhesive tape article in a long length or a roll that can be cut into discrete strips having any selected length, wherein each strip can be provided with a pull tab or stretch removal tab that can be grasped and pulled by a user to remove the adhesive tape from a substrate.
The present invention relates to various embodiments of a stretch releasing adhesive tape with a geometry that provides differential adhesive properties in a compressed state and an uncompressed state. Adhesion and tack can thus be controlled by varying the amount of compression. Additionally, the present stretch releasing adhesive tape can be easily repositioned prior to compression. A portion of the present stretch releasing adhesive tape can be left in the uncompressed state, thereby providing one or more pull tabs. The stretch releasing adhesive tape of the present invention can be provided in strips of varying lengths, in roll form, or in a stack.
In one embodiment, the stretch releasing adhesive tape article includes an elongated length of stretch releasing adhesive tape with side surfaces comprising at least one potential contact surface area. At least a portion of the potential contact surface area comprises an adhesive surface having raised portions. The potential contact surface area comprises a first interface surface area in the uncompressed state and a second interface surface area greater than the first interface surface area in the compressed state. The stretch releasing adhesive tape in the uncompressed state can operate as a pull tab.
In another embodiment, the stretch releasing adhesive tape article comprises an elongated length of stretch releasing adhesive tape with adhesive on all side surfaces. The side surfaces have at least one potential contact surface area. The potential contact surface area has a first interface surface area in an uncompressed state and a second interface surface area greater than the first interface surface area in a compressed state.
In one embodiment, the stretch releasing adhesive tape comprises a multi-layered structure. The stretch releasing adhesive tape can have one or more elastic or inelastic structural members. The structural member can be foam, film, a monofilament or a variety of other materials. A film can optionally be interposed between the adhesive and the structural member or located at the interior of the structural member. The stretch releasing adhesive tape can be one of a pressure sensitive adhesive tape with an elastic structural member, a pressure sensitive adhesive tape with a highly extensible and substantially inelastic structural member, or a solid pressure sensitive adhesive.
In the various embodiments, the potential contact surface area in the uncompressed state can be a plurality of raised portions, a non-planar structure, a discontinuous surface, or combinations thereof The stretch releasing adhesive tape in the uncompressed state comprises a cross-section selected from circular, star-shaped, oval, multifaceted or any other geometric shape that provides less surface area in the uncompressed state than in the compressed state. In another embodiment, the potential contact surface area comprises a rectangular cross-section of stretch releasing adhesive tape twisted to form helical ridges. The potential contact surface area can have adhesive regions and non-adhesive regions.
The elongated length of stretch releasing adhesive tape can be segments or a roll. A release liner may optionally be used. Frangible connections can be formed intermittently along the stretch releasing adhesive tape.
The present invention is also direct to a method of using a stretch releasing adhesive tape article with differential adhesive properties, including the steps of positioning a potential contact surface area of an elongated length of stretch releasing adhesive tape on a substrate to form a first interface surface area; compressing a portion of the stretch releasing adhesive tape to form a second interface surface area, the second interface surface area being greater than the first interface surface area; and retaining an uncompressed portion of the stretch releasing adhesive tape as a pull tab.
In another method the steps include providing an elongated length of stretch releasing adhesive tape with a generally rectangular cross section; twisting at least a portion of the stretch releasing adhesive tape to form a twisted portion with a plurality of helical ridges; positioning the stretch releasing adhesive tape on a substrate, the twisted portion defining a first interface surface area; compressing an untwisted portion of the stretch releasing adhesive tape against the substrate to form a second interface surface area greater than the first interface surface area; and retaining the twisted portion in an uncompressed state to form a pull tab.